Well, I menu plan all three meals and pretty much cook every meal. The way you make it easier is to plan certain things that you can rely on every day...Do things that are consistent.
For instance, I know that every lunch, we will have vanilla yogurt and fresh or frozen fruit, so I always have that on hand. I can buy big packages of it and just slap it on the plate with the one cooked option. I make a big batch of muffins and freeze them, rotating out the kind every week. On a morning I don't feel up to par, I can nuke them and serve with fruit and milk. I also use a box of cereal for these days. Since the cereal is not an everyday thing, it can last for a little over a month. Serve it with fresh or frozen fruit, also.
I also do the whole roasted chicken thing (this week as a matter of fact). I buy a 5 dollar whole chicken (big as I can find) at the grocery store. I roast it, and serve it (one small piece per person) with potato casserole, rolls and green beans for two days. The rest of the meat is picked off and placed in a different container. I use that for chicken salad sandwiches. I only serve each person a half a sandwich, as they get yogurt and fruit with it for lunch, and this cuts down on the amount of meat and bread we use. The chicken that is not used is kept in the fridge. All the remnants of the chicken (including what was left on people's plates) goes into a big stock pot with remnants from various veggies I keep in the freezer instead of throwing away. I cover it with enough water to cover and add a little organic ACV to pull out all the nutrients. Once it is cooled, pull out all the bones and skin. Pick off any more meat that will come off and throw away the left bones and skin. Take the veggie ends and pieces out and toss as well. Add fresh veggies to the stock and boil down until it reduces. Add any left over meat to this as well as any pasta or rice you have lying around. Fresh half and serve half for lunches for a few days.
If there is any left when people get sick of it, strain out meat, veggies, pasta/rice, and mix with fresh cooked pasta/rice, can of cream of chicken, and a little bit of the stock and place in a casserole. Top with cheese.
This made 2 meals of roasted chicken, one lunch of chicken salad, one lunch of soup, and one dinner of casserole. You also have one frozen soup to use next week, for either lunch or dinner.
Last week I used the left over soup and added a seasoning packet of each ranch mix and half of a taco seasoning one. I also added a can of corn, black beans, and rotel. This made southwestern chicken soup. Forze half, served it again later. Once it was heated, I added in a small block of velveeta and served with tortilla chips.
So for dinner those nights, I only bought the add ins.
Also, I make a big batch of brownies, cupcakes (keep unfrosted), cookies and no bake cheesecake on hand in the freezer. When it is time to get another snack out for the week, I just grab one of the things out of the freezer and place in the fridge. If something needs to be frosted, no it then. This cuts down on having to constantly think or cook snacks.
I generally spend about 50-60 dollars a week to feed the three of us and have PLENTY left in the fridge. This covers, snacks, drinks,fruit and veggies, three meals a day, and I add to my stock of snack mixes every week.
Also, I plan out two to three weeks at a time, and shop once a week, so when I plan on one side of a paper, on the other is the shopping list. If I have something on the list left over, I just cross it off before I go. This cuts down on all the time I spend thinking about it. Open the binder, grab this weeks sheet, and run out the door.
I hope you can find your groove.